Space not only physically impacts astronauts’ body and brain but also cause changes to certain gut “bugs,” according to a new research.

A team of researchers at Northwestern University studied the gut bacteria of NASA astronauts Scott Kelly and Mark Kelly, identical twin brothers who are part of a unique human study, and found that changes occur to gut bacteria in space.

Turek, co-authored the study, said, “We are seeing changes associated with spaceflight, and they go away upon return to Earth … It’s early in our analysis, so we don't know yet what these changes mean. We don’t know what it is about spaceflight that is driving the changes in gut microbes.”

The research team included experts from Rush University Medical School and the Chicago-based University of Illinois. The researchers said that they would work closely with the other teams to piece together a more complete picture of the effects of extended space missions on human body.

They also expressed hope that their findings would help in safeguarding the health of astronauts in space as well as improving human health on Earth.

The Northwestern University team of researchers is one of ten NASA-funded research groups that have been assigned the task of studying the Kelly twins to determine how extended space missions, such as a mission to Mars, could affect the human body. Scott Kelly spent around a year in space, while his brother, Mark Kelly, remained on Earth, to help researchers find out the differences.